A directional light in this engine shines along its own -Y axis. I had been aiming every sun in the project as though it shone along -Z, which is what the other engine I have most of my habits from does.

The effect is not an error message. It is a scene that looks slightly wrong in a way you attribute to everything else. What I had set as midday arrived nearly horizontal, so noon in a captured street looked like late afternoon, and I spent real time deciding that splat captures just do not take a hard overhead light well. They take it fine. I had never once given them one.

This is the failure mode I find hardest to defend against. A crash tells you where it is. A wrong constant in a coordinate convention produces output that is plausible, consistent, and consistently wrong, and every judgement you make downstream of it is made in good faith on bad ground. The sun axis was not discovered by a test. It was discovered by finally asking why a number that should have been obvious kept needing a fudge factor next to it.

Everything lit got re-checked against a correctly aimed sun. Several opinions I held about how captures respond to light did not survive.